A team of Australian scientists have unveiled a ground-breaking study that identifies, for the first time, the exact source of diamond-bearing rocks known as orangeites.
The paper reveals that orangeites —until now believed to be common only to South Africa— may be present in much higher abundance worldwide
Published Monday in the April edition of Nature Communications, the paper reveals that orangeites —until now believed to be common only to South Africa— may be present in much higher abundance worldwide, especially in Australia.
Rough on the outside, these rocks contain not only treasured diamonds but also tiny fragments of mantle and crustal rocks. By using highly sophisticated geochemical and isotopic analytical techniques, the scientists were able to link those fragments to the source of the orangeites, deep in the interior of the planet.
“We found strong evidence that orangeites are sourced from MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) mantle, which up until recently had only been recognised in South Africa,” leading author, Professor Fiorentini — from The University of Western Australia — said in a statement. “However, ongoing studies suggest that MARID mantle may occur in other continents, including here in Australia.”
The group also found evidence that suggests orangeites were formed from lava produced by massive volcanic eruptions several tens of millions of years ago. Until now, the common belief was that diamonds were formed about 990 million years ago.